Лако-красочные материалы — производство

Shelf life — this is the period for which the unmixed adhesive components may be stored without undergoing significant deterior­ation. Most structural adhesives have shelf lives in excess of six months and maybe up to several years. Shelf life is often extended by storage at low temperature, for example in a refrigerator. It is usually […]

The engineer will be concerned with the behaviour and performance of the selected adhesive from the time he first purchases it from the manufacturer, through the mixing, application and curing phases to its properties in the hardened state within a joint over the intended design life. Thus the properties of interest in approximate chronological order […]

Although not strictly used as prime structural adhesives, polymer latices or dispersions have been included here because of their increasing use as aids to bonding in the patch repair of spalled concrete. They usually take the form of a polymer-cement slurry which is applied to the moistened and prepared concrete surface. In general, the repair […]

The original development of polyurethanes was relatively slow due to early competition from more favourable epoxy formulations. However, in the 1950s and 1960s work on surface coatings suggested that polyurethanes were capable of being formulated to achieve a wide variety of performance properties, some of which were appropriate to applications as adhesives. Nowadays uses are […]

The liquid acrylics form a further group of unsaturated reactive resins and these are now available as two-part mixed or unmixed products. Compared with polyesters they are a relatively recent addition to the range of adhesives potentially suitable for structural joints. Many are based on the monomer methylmethacrylate which is polymerised by the addition of […]

Whereas in epoxies the ‘hooks’ are provided by the resin and the ‘eyes’ by the hardener, in polyesters both ‘hooks’ and ‘eyes’ are located in the unsaturated resin(9). The addition of a curing agent or catalyst based on organic peroxide initiates the chemical reaction and promotes cross-linking within the resin. Unsaturated acids are Fig. 2.4. […]

Fillers. In practice most epoxy resin systems have fillers incorpor­ated, often simply to reduce cost although they may also assist in gap filling, reduction of creep, reduction of exotherm, corrosion inhibition and fire retardation. Their incorporation will also alter the physical and mechanical properties of the adhesive. Construction resins in particular often include a large […]

Aliphatic polyamines. These are one of the most commonly used hardeners in room temperature curing epoxy adhesives. With glycidyl ether resins only relatively small quantities (6-12 parts per hundred of resin) are required, although sometimes the rate of reaction may be a little too fast for convenience, particularly in conditions of high ambient temperature. The […]

Epoxy resins Epoxy resins have only been available commercially since the Second World War and are traditionally based upon the reaction of epichlorohydrin on bis-phenol A, to give a liquid compound of Glycidyl Ether Ether Hydroxyl Ether Ether Glycidyl group bond bond group bond bond group Epoxy Bisphenol “A” Bisphenol “A” Epoxy group group group […]

2.1 Engineering and non-engineering adhesives Adhesives may be classified as either organic or inorganic materials in a number of different ways; for example by origin, by method of bonding, by end use or on a chemical basis (1). Table 2.1 gives a broad classification of the organic adhesives based upon origin under the general headings […]